The effect of manufacture and assembly joining methods on stiffened panel performance

This paper describes the simulation of representative aircraft wing stiffened panels under axial compression loading, to determine the effects of varying the manufacturing shape and assembly joining methods on stiffened panel performance. T-stiffened and Z-stiffened panels are modelled in Abaqus simulating integral, co-cured and mechanically fastened joints. The panels are subject to an edge compressive displacement along the stiffener axis until failure and the ultimate failure load and buckling performance is assessed for each. Integral panels consistently offer the highest performance. Co-cured panels demonstrate reduced performance (3-5% reduction in ultimate load relative to integral) caused by localised cohesive failure and skin-stiffener separation. The mechanically fastened panels are consistently the weakest joint (19-25% reduction in ultimate load relative to integral) caused primarily by inter-rivet buckling between fasteners

Methods for Optimal Work Instruction Delivery: Pictograms v Images

This paper focuses on quantifying the benefits of pictogram based instructions relative to static images for work instruction delivery. The assembly of a stiffened aircraft panel has been used as an exemplar for the work which seeks to address the challenge of identifying an instructional mode that can be location or language neutral while at the same time optimising assembly build times and maintaining build quality. Key performance parameters measured using a series of panel build experiments conducted by two separate groups were: overall build time, the number of subject references to instructional media, the number of build errors and the time taken to correct any mistakes. Overall build time for five builds for a group using pictogram instructions was about 20% lower than for the group using image based instructions. Also, the pictogram group made fewer errors. Although previous work identified that animated instructions result in optimal build times, the language neutrality of pictograms as well as the fact that they can be used without visualisation hardware mean that, on balance, they have broader applicability in terms of transferring assembly knowledge to the manufacturing environment.

Design Optimisation for Compression Moulded Sheet Moulded Compounds

This paper builds on previous work to show how using holistic and iterative design optimisation tools can be used to produce a commercially viable product that reduces a costly assembly into a single moulded structure. An assembly consisting of a structural metallic support and compression moulding outer shell undergo design optimisation and analysis to remove the support from the assembly process in favour of a structural moulding. The support is analysed and a sheet moulded compound (SMC) alternative is presented, this is then combined into a manufacturable shell design which is then assessed on viability as an alternative to the original.
Alongside this a robust material selection system is implemented that removes user bias towards materials for designs. This system builds on work set out by the Cambridge Material Selector and Boothroyd and Dewhurst, while using a selection of applicable materials currently available for the compression moulding process. This material selection process has been linked into the design and analysis stage, via scripts for use in the finite element environment. This builds towards an analysis toolkit that is suggested to develop and enhance manufacturability of design studies.

DEVELOPING AN INTELLIGENT DIGITAL MOCK UP TO INTEGRATE DESIGN AND MANUFACTURING DISCIPLINES

This paper presents an approach to develop an intelligent digital mock-up (DMU) through integration of design and manufacturing disciplines to enable a better understanding of assembly related issues during design evolution. The intelligent DMU will contain tolerance information related to manufacturing capabilities so it can be used as a source for assembly simulations of realistic models to support the manufacturing decision making process within the design domain related to tolerance build ups. A literature review of the contributing research areas is presented, from which identification of the need for an intelligent DMU has been developed. The proposed methodology including the applications of cellular modelling and potential features of the intelligent DMU are presented and explained. Finally a conclusion examines the work to date and the future work to achieve an intelligent DMU.